Are you using regular pasteurized, homogenized, whole milk?

Non-fat and low-fat milk will remain quite soft and you may miss the signs that your milk has finished culturing. When activating your starter using whole milk, be sure your milk is homogenized. If not, scoop out some of the fat before beginning the culturing process. It’s much easier to activate the starter in homogenized milk.

If you are outside the US, your milk may not be required to state that it is Ultra Pasteurized. Ultra Pasteurized and UHT milk are heated to such high temperatures, the heirloom cultures may not perform reliably. Call the dairy to learn more about the pasteurization temperature.

How much milk are you using?

To activate the culture, use 1 packet in 1-2 cups of milk. We completely understand the desire to make large batches! Heirloom yogurts do require an activation, or “wake up” period, though, Rushing may result in having to start over with a new starter.

After activation, you can make as much as 2 quarts (one half-gallon) per batch. Heirloom cultures do not do well with larger batches.

How much culture are you using?

Never use more than one packet to activate. After activation, never use more than 1 tablespoon of starter per cup of milk. While it is tempting to use more for a “stronger” yogurt, this is not the case. Too much starter will cause the yogurt to fail and kill the starter.

What is the temperature in the space you are culturing? Have you verified that the temperature is being maintained?

In cooler months, you may need to find a warmer location. The yogurt will not activate at temperatures below 68ºF

To test the temperature in the culturing area, place a cup of tap water in the area for 24 hours. Then periodically measure the temperature of the water using a kitchen thermometer over the next few days. Don't forget to test the temperature at night and throughout the year.

How long are you culturing?

The initial activation batch may take up to 48 hours, but be sure to start checking periodically after 24 hours.

Once your starter is active, do not allow your starter to sit longer than 18 hours. If your yogurt is not setting, check the temperature, and amount of starter.

If you need to culture your yogurt for longer than 18 hours, remove enough yogurt to start your next batch as soon as it sets. This will allow you to keep a nice, strong “mother culture” for you next batch while still achieving the very tangy yogurt of a long culturing time.

How long is your starter stored between batches?

Be sure to culture your yogurt at least every 7 days.

If it’s been up to 10-14 days without making a batch, try a small batch with 1 tablespoon of yogurt in 1 cup of milk. If this sets, make a second batch within 2 days to strengthen your starter.